The present invention is directed generally to novel systems and methods for performing sputter deposition, and to optical devices manufactured using such systems and methods.
The present invention relates to ion beam sputter deposition (IBSD). More particularly, the present invention concerns a system and method for performing sputter deposition using a divergent ion beam source. It is believed that IBSD is a common technique in the manufacturing of optical filters.
The method is normally carried out in a vacuum environment by bombarding a target with ion current. The bombardment results in the dislodging of atoms from the target which are then deposited as a film on a substrate. IBSD is an improvement over other types of sputter deposition techniques because it produces films of high quality with improved adhesive properties. IBSD produces sputtered films that have a density very similar to the bulk density of the materials used and a surface roughness which is equal to that of a super-polished substrate. these results are advantageous for optical coatings.
Performance of optical filters is further improved with deposition thickness that is uniform across the substrate. The disclosed system and method provide such an improvement.
The present invention is directed to a system and method for performing sputter position on a substrate. First, second, and third divergent ion current sources generate first, second and third divergent ion beams, respectively. The substrate faces the first ion current source. The first target faces the second ion current source, and the second target faces the third ion current source. The central axis of each ion current source is orthogonal to the central axes of the other two ion current sources.
In one embodiment, the magnitude of the ion current produced by each given ion current source varies throughout the source""s respective ion beam in accordance with the equation: ion current=J0 cos (xcex8); wherein xcex8 is an angle between the central axis of the given ion current source and a direction of ion current from the given ion current source, and J0 is an ion current density along the central axis of the given ion current source.
In one embodiment, the first and second targets are negatively biased and the substrate rotates during operation of the system. In this embodiment, the central axis of the first ion current source coincides with the axis of rotation of the substrate, which is perpendicular to the surface of the substrate and passes through the substrate at its center. Also in this embodiment, the substrate has a surface which is normal to the central axis of the first ion current source, the first target has a surface which is normal to the central axis of the second ion current source, the second target has a surface which is normal to the central axis of the third ion current source, the central axis of the first ion current source passes through the center of the substrate, the central axis of the second ion current source passes through the center of the first target, and the central axis of the third ion current source passes through the center of the second target.
The present invention is further directed to an optical filter that results from the practice of the disclosed system and method.